An engine may be operated with a fuel injection system that is temporarily deactivated in response to engine operating conditions. The fuel injection system may be deactivated to reduce energy consumption of a vehicle. For example, fuel injection may be temporarily deactivated during vehicle deceleration when engine torque may not be needed. Further, in engine systems that include two or more fuel injection systems, one fuel injection system may be temporarily deactivated while the other injection system continues to deliver fuel to the engine. By deactivating one fuel injection system, it may be possible to reduce energy consumption of the vehicle. However, if components of a fuel pump of the fuel injection system continue to move while the fuel injection system is deactivated, performance of the fuel pump may degrade over time.
The inventors herein have recognized the above-mentioned disadvantages and have developed a method for operating a fuel pump, comprising: diagnosing operation of a fuel pump driven solely mechanically in response to an electrical property between a motive force component of the fuel pump and a stationary component of the fuel pump.
By assessing an electrical property of a mechanically driven pump it may be possible to determine whether or not the mechanically driven pump is degraded and/or is being lubricated during times where flow through the mechanically driven fuel pump is low. An electrical property between two components of a fuel pump can be an indication of pump degradation and lubrication. Thus, the electrical property can be a basis for diagnosing and controlling flow through the fuel pump. For example, some fuel pumps include a piston that provides pressure to fuel passing through the fuel pump. The piston may be constrained via a fuel pump housing or cylinder within which the piston moves. An electrical resistance or capacitance between the piston and the housing or cylinder may be a basis for determining fuel pump degradation and whether or not the fuel pump is being lubricated when flow through the fuel pump is low. If the electrical resistance of the fuel pump is low, it may be an indication that there is little fuel between the piston and the cylinder wall providing lubrication to the fuel pump. Fuel pump lubrication may be increased to limit fuel pump degradation by increasing fuel flow through the fuel pump in response to the low electrical resistance level.
The present description may provide several advantages. In particular, the approach may provide for an increased level of lubrication between moving parts of a fuel pump so as to reduce fuel pump degradation. In addition, the approach may help to conserve fuel since the fuel pump can be operated at higher pumping capacities only when scheduled by engine operating conditions or when a low level of pump lubrication is indicated. Further still, the present description provides for diagnosing a fuel pump in response to an electrical property of the fuel pump.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.